MinimumIncrement is an AT-SPI-ism that has no counterpart in the ARIA
specification, so it should not live inside public API. Additionally,
it's not really a useful method because it collapses two values on the
adjustment API.
The only method in the GtkAccessibleRange interface should be the
set_current_value(), which allows ATs to control the current position in
a ranged widget.
The AT-SPI implementation can now use all the accessible properties,
including the VALUE_TEXT one, mapped to the Text property on the
AtSpi.Value interface.
This requires some cleanup to remove assumptions
about accessibles being widgets in the backend,
and some code to navigate the tree with these
extra objects in between widgets.
The accessibles for stack pages have the role
GTK_ACCESSIBLE_ROLE_TAB_PANEL. This is the first
step towards implementing the tabs patterns
as described in the aria authoring guidelines
for GtkStack.
